1. Technical Field
The present invention relates to improvements in a piezoelectric oscillator having a structure in which a semiconductor device is bonded to a container of a piezoelectric resonator containing a piezoelectric resonator element, and a method for manufacturing a piezoelectric oscillator.
2. Related Art
A piezoelectric resonator or a piezoelectric oscillator has been widely used in small-size information apparatuses such as hard disk drives (HDDs), mobile computers, and IC cards and mobile communication apparatuses such as cell phones, car phones, and paging systems. A piezoelectric oscillator is formed by bonding together a piezoelectric resonator element made of a piezoelectric material and a semiconductor device, that is, an IC chip.
JP-A-2006-60638 shows an example of a piezoelectric oscillator. In a quartz crystal oscillator shown in FIG. 1 of JP-A-2006-60638, an IC chip 5 is bonded to a mount substrate 2 with a bump 6 therebetween. A piezoelectric resonator 1 is bonded to an external coupling terminal of the IC chip 5 with solder 9 therebetween.
By bonding together the IC chip 5 and piezoelectric resonator 1 in such a manner that these elements overlap each other vertically as described above, there is provided a piezoelectric oscillator (quartz crystal oscillator) that is made compact in the horizontal direction and thus has a reduced mount area.
However, in the quartz crystal oscillator described in JP-A-2006-60638, the external coupling terminal of the IC chip 5 bonded to the piezoelectric resonator 1 has a flat structure and a limited bonding area. Accordingly, there occurs a problem that the reliability with respect to the electrical coupling between the IC chip and piezoelectric resonator is reduced. This problem becomes more significant as the IC chip and piezoelectric resonator are made smaller.